88 FLORA INDICA. petals imbricated in aestivation. This important character was first indicated by Benthara, in the Niger Flora. A second tribe', which we propose to call Nitr&phorea, has been indicated by Mr. Bennett, in bis valuable remarks under Saccopetahmi in Horsfield's * Plantse Javanicse Kariores.' "It comprises a nnmber of genera, in which the inner petals are more or less unguiculate at the base.- In Orophea and Mitrephora, which may be considered the typical genera of this tribe, the claw is long and slender; but in others, which appear to form £ transition to the typical genera of Anonacea, it is very short and much broader. A third aberrant tribe has also been indicated by Mr. Bennett; it comprises the genera Afyhonsea, Saccopetalum^ and Rfiliusa. Mr. Bennett has characterized this tribe by the small size of the outer petals, -and by their similarity to the calyx; but in the 'genus Alphonsea^ which evidently forms a part of it, this character is not pre- sent while it occurs in PJi&antkus, which cannot be separated far from Gvatteria, as well as in some other species not naturally allied to the genera above mentioned. The true character of the tribe, we think, lies in the shape and structure of the anthers, which, instead of being den 3ely -wedged together as in the other tribes, are broadly oval or oblong, with large short cells, and a small terminal apiculus of cnn- nectivuia. These anthers rise above one another in a laxly imbricated manner, so that the greater part of each is exposed; whereas the normal stamen of the Order is erect and columnar, with the dilated process of the connective alone visible, while the linear anther-cells are completely concealed. 3fcnodore&3 which we propose to regard as a fourth trihe, contains only a single species, characterized by the distribution of the ovules over the whole surface of the solitary ovary. This very remarkable structure, which is very fcire among plants, occurs hi the nearly allied family LartUsabalees, to wliich this tribe exhibits au in- teresting transition. It is found also, curiously enough, in the apocarpous mouo- cotyledonous Order Butomacetf. Ihe remarkable Australian genus jBupomatia, described by Mr. Brown in * Flin- ders' Voyage/ and referred By him without doubt to Anonace<e, uannct surely be b<»- parated from the remainder of the Order, but forms a fifth aberrant tribe, the well known characters of which it is unnecessary to repeat here. We believe that this interesting plant has not been found by any botanist but its illustrious disco- verer, and though it has been introduced into our conservatories, it has never flowered there. lathe remainder of the Order the perianth is valvate iu activation, the petals arc never unguiculate, the anthers are numerous and densely packed, and the ovules are either erect from the base of the ovary, or arise from the ventral suture. This combination of characters, marking the typical Anonacea,, is present in about one- half of the Indian species, and in a muc^ larger proportion of those of America. Among these, Anonea, with the ovaries cohering together iu the flower, and after- wards developed into a compound fruit, form a well-marked tribe. The remaining genera we propose to divide into two tribes, Xylopiea, with thick fleshy inner petals, which are triquetrous, except at the base, and Guattff/ie&, with coriaceous inner petals, not materially different in shape or texture from the outer ones. These tribes appear to us very natural; but they pass by such insensible gradations into one another, that the limit between the two is quite arbitrary. In the formation and circumscription of the genera, it has been our aim in the first instance to bring together those species which possess a similar habit, and which -ap- pear to us to form natural groups, and to select as generic distinctions such characters as are common to the species thus associated. This has led us. to study with care the relative importance of the floral organs, and we have in consequence made considerable alterations in the limits of the genera. We cannot expect that the conclusions at which we have arrived will be final, as our attention has been coufmed almost en- tirely to the Asiatic forms; but it may be serviceable to the future monographist of this difficult Order, to state the degree of value we are disposed to attach to each character.